The present invention relates to winding and, more particularly, to winding tape on cores to build roll packages of tape.
Tape, especially plastic tape, has become commonplace in a number of products including electrical products such as wire, cable, conduit, transformers and other electrical components, general purpose tapes and packaging. The use of plastic tape as ties in plastic garbage and storage bags has grown significantly. Manufacturers utilize plastic tape in the form of rolls in automated machinery to produce a wide range of such products.
Rolls of plastic tape are normally wound on cores to aid in winding and provide improved stability of the roll. They are sometimes wound as a single xe2x80x9cpancakexe2x80x9d package which comprises a single roll having a width equal to the width of the plastic tape or film. Such a roll has the disadvantage of becoming unstable at large roll outer diameters, especially if the tape is narrow. The single roll package also limits the length of plastic tape, requiring frequent stopping of the machinery for roll changes.
Another winding method for roll packages utilizes a spool package that employs a continuous helical winding that alternates in direction similar to winding a reel of fishing line or string. This method produces a roll package with a width greater than the tape width and provides additional capacity of the roll package as compared to the xe2x80x9cpancakexe2x80x9d roll package. This method results in a condition of xe2x80x9csoftxe2x80x9d ends resulting from voids between the windings at the roll ends caused by the helical pattern. This winding method suffers the disadvantage of instability, and limits the diameter to which the roll package may be wound. Use of spools with end discs improves the stability, but increases the complexity, cost and weight of the package.
U.S. Pat. No. 4,568,033 discloses a tape package comprising a winding method which incorporates a flanged portion and a central helical traverse portion. The wind portions are built up from a plurality of windings to form steps. The height of the step is limited by the ability of the tape to traverse the steps. U.S. application Ser. No. 09/370,677 hereby incorporated by reference, discloses a multi-segment roll package that utilizes a novel pattern of end, center and intermediate roll segments made up of winding groups separated by helical transition windings.
Therefore, an object of the present invention is to provide a roll package having a high wrapping density, increasing the length of tape in a given package outer diameter.
A further object of the present invention is to provide a roll package that may be wrapped to larger roll diameters, increasing the capacity of the roll package.
A further object of the present invention is to provide a roll package with improved mechanical stability, reducing the reject rate of roll packages due to damage.
Yet another object of the present invention is to provide a roll package that combines the advantages of the simple spooled roll package and the high-density multi-segment roll packages of earlier designs.
The roll package of the present invention includes a continuous length of tape wrapped as a conventional spooled roll segment sandwiched between two outer or end roll segments. The end roll segments and the spooled roll segment are wrapped on a common core and share a common winding axis. The end roll segments are built up from spiral winding groups of one or more zero-pitch spiral windings interrupted or separated by helical transition windings which transition to and from the spooled roll segment. The helical pitch of the transition windings is greater than the helical pitch of the spooled roll segment. The spooled roll segment is built up from layers of helical spool windings of a predetermined pitch. In the preferred embodiments, the spooled roll segment is at least two tape widths wide. The end segments are substantially one tape width wide.
In the preferred embodiments, the helical pitch of the transition windings is greater than the tape width. A high transition winding pitch, greater than the spool pitch of the center spooled roll segment, aids in transitioning the xe2x80x9cstepxe2x80x9d or difference in height created during the build-up of the segments. The high transition winding pitch reduces humps or distortions that would otherwise result.
In the preferred embodiments, the roll package is made by wrapping one or more spiral windings at the first end segment position, wrapping a helical transition winding to the beginning of the spooled roll segment, wrapping a layer of helical spool windings at a spool pitch to the end of the spool roll segment position, wrapping a helical transition winding to the second end segment position and wrapping one or more spiral windings at the second end segment position. The axial direction of the windings is then reversed and the wrappings of spooled and end windings are repeated to the first end in a similar manner. The process is repeated until the roll package is wrapped to the desired diameter.
A second embodiment of the roll package incorporates one or more intermediate roll segments disposed between the spooled roll segment and the end segments. The intermediate roll segment is similar to the end roll segment except that the relative number of spiral windings in each winding group is approximately one half of the end roll segments. Helical transition windings connect the intermediate winding groups to the end winding groups and the spooled winding layers.
The high-pitch helical transition windings act as connectors between the end roll segments and the spooled roll segment or the end roll segments, intermediate roll segments and spooled segments. The combined structure results in a package which eliminates the xe2x80x9csoft endxe2x80x9d problems of a conventional spooled roll package and allows larger diameter packages than would be practical with conventional spooled packages.